/// Copyright (c) 2019 Razeware LLC
///
/// Permission is hereby granted, free of charge, to any person obtaining a copy
/// of this software and associated documentation files (the "Software"), to deal
/// in the Software without restriction, including without limitation the rights
/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
/// copies of the Software, and to permit persons to whom the Software is
/// furnished to do so, subject to the following conditions:
///
/// The above copyright notice and this permission notice shall be included in
/// all copies or substantial portions of the Software.
///
/// Notwithstanding the foregoing, you may not use, copy, modify, merge, publish,
/// distribute, sublicense, create a derivative work, and/or sell copies of the
/// Software in any work that is designed, intended, or marketed for pedagogical or
/// instructional purposes related to programming, coding, application development,
/// or information technology.  Permission for such use, copying, modification,
/// merger, publication, distribution, sublicensing, creation of derivative works,
/// or sale is expressly withheld.
///
/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
/// THE SOFTWARE.

import Foundation

class AppModel {

  static let instance = AppModel()

  let dataModel = DataModel()

  private(set) var appState: AppState = .notStarted {
    didSet {
      stateChangedCallback?(self)
    }
  }

  var stateChangedCallback: ((AppModel) -> ())?

  // MARK: - App Lifecycle
  func start() throws {
    guard dataModel.goal != nil else {
      throw AppError.goalNotSet
    }
    appState = .inProgress
  }

  func pause() {
    appState = .paused
  }

  func restart() {
    appState = .notStarted
    dataModel.restart()
  }

  func setCaught() throws {
    guard dataModel.caught else {
      throw AppError.invalidState
    }
    
    appState = .caught
  }

  func setCompleted() throws {
    guard dataModel.goalReached else {
      throw AppError.invalidState
    }

    appState = .completed
  }
}

